Spearmint (Mentha spicata) is a fragrant perennial herb known for its glossy, spear-shaped leaves and bright, refreshing flavor. It is easy to cultivate, offering a continuous supply of leaves for culinary uses, such as teas, cocktails, and flavoring food. Spearmint is easy to grow and maintain, even for novice gardeners, provided its vigorous nature is managed.
Methods for Starting Spearmint
The easiest approach to starting spearmint is by planting an established transplant purchased from a garden center, typically in mid-spring to early summer. Stem cuttings offer a simple way to propagate from an existing plant. To take a cutting, select a healthy, four to six-inch stem that has not flowered, cutting just below a leaf node.
Cuttings can be rooted in water or directly in soil. Placing the prepared stems in a glass of water, with leaves above the surface, usually results in roots forming along the submerged stem within one to two weeks. Alternatively, insert cuttings into moist, well-draining potting soil and keep them out of direct sunlight until roots establish. Starting spearmint from seed is the least common method, as seeds often produce plants that are not true to the parent variety. If using seeds, sow them thinly on the surface of damp seed compost and keep them warm (70 to 75°F) until germination.
Establishing the Ideal Growing Environment
Spearmint thrives in conditions that mimic its natural habitat, preferring a location with full sun to partial shade. Placing the plant in full sun (at least six hours of direct sunlight) encourages the production of essential oils, resulting in a more intense flavor. The ideal soil is rich, moist, and well-draining, with a pH that is slightly acidic to neutral (6.0 to 7.5). Adding organic matter, such as compost, improves fertility and moisture retention capacity.
Consistent watering is necessary, as spearmint prefers the soil to remain evenly moist, but not waterlogged, which can lead to root rot. Saturate the soil thoroughly and allow the top inch or two to dry slightly before watering again. Spearmint has minimal fertilization needs, often thriving without supplemental feeding. A light application of balanced fertilizer or top-dressing with organic compost in the spring is usually sufficient to support its growth.
Controlling Aggressive Growth
Spearmint spreads aggressively through horizontal underground stems called rhizomes, which quickly colonize garden beds. The most effective strategy to manage this invasiveness is to plant spearmint in containers, even if placed directly into the ground. Select a container at least eight inches in diameter. For in-ground containment, sink a bottomless pot deep into the soil, keeping the rim an inch or two above ground to prevent rhizomes from escaping.
Regular maintenance through pruning manages the plant’s size and encourages a bushier form. Pinching off stem tips and frequently harvesting redirects the plant’s energy from spreading outward to growing upward. This practice should include removing any flower buds before they bloom, as flowering reduces the concentration of flavorful oils in the leaves. Good air circulation helps prevent issues like powdery mildew, while regular inspection catches pests such as spider mites.
Harvesting and Preservation
The best time to harvest spearmint for maximum flavor and aroma is just before the plant begins to flower, when the concentration of essential oils is at its peak. Harvesting should be done in the early morning, after the dew has dried but before the sun is at its hottest, as cooler temperatures help preserve the volatile oils. To harvest, use sharp shears to cut the stems just above a leaf node; this encourages new growth to sprout from that point, ensuring a continuous supply of fresh leaves.
For long-term storage, spearmint leaves can be either dried or frozen. Drying is best for leaves intended for tea, and this can be accomplished by air-drying small bunches in a warm, dark, and well-ventilated area for one to two weeks, or by using a dehydrator set to a low temperature (95 to 105°F). Alternatively, the fresh leaves can be frozen, which better preserves the bright flavor for culinary use. Chop the leaves, pack them into ice cube trays, and cover them with water before freezing to create convenient portions.